It's really painful to lose artwork files or lose active progress in an opened Illustrator file. There are two options available for auto-saving progress in an opened Illustrator document. Astute Graphics' Auto Savior is a free plugin for Illustrator that has been available for at least several years. Illustrator now also has the built-in ability to auto-save recovery data in open documents within Preferences (under File Handling and Clipboard).
In broader file management practices I strongly recommend doing regular, daily back-ups of art files in use. Even backing up onto volumes that are off premise. External hard discs are great for backups. But if the office burns down in a fire and the backup hard drive is sitting there on the desk next to the office computer both data volumes are literally going to be toast. Cloud storage is one alternative. I work in a small business and store secondary copies of my work at home (that wouldn't be so great in a larger business).